What might account for a soldier experiencing syncope after standing at attention for a long period of time?
Increased respiratory rate.
Vasoconstriction.
Increased heart rate.
Venous pooling.
The Correct Answer is D
Choice D rationale
Venous pooling, particularly in the lower extremities, commonly occurs when standing still for prolonged periods due to the effects of gravity and reduced skeletal muscle pump activity. This pooling decreases venous return to the heart, leading to reduced cardiac output and consequently a drop in cerebral blood flow, which can result in syncope (fainting).
Choice A rationale
Increased respiratory rate (hyperventilation) typically leads to a decrease in carbon dioxide levels, causing respiratory alkalosis. While severe hyperventilation can lead to cerebral vasoconstriction and lightheadedness, it is not the primary physiological mechanism for syncope after prolonged standing.
Choice B rationale
Vasoconstriction, particularly systemic arteriolar vasoconstriction, would generally help maintain blood pressure by increasing total peripheral resistance, counteracting a drop in blood pressure. Therefore, it would typically prevent rather than cause syncope in this scenario, unless it was a compensatory, insufficient response.
Choice C rationale
An increased heart rate is a compensatory mechanism to maintain cardiac output when venous return or stroke volume is reduced, such as during orthostatic stress. While the heart rate does increase, it is often insufficient to prevent the fall in blood pressure that leads to syncope if venous pooling is severe.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
Positive feedback mechanisms amplify the initial stimulus, leading to an increased response. While important in certain physiological processes like childbirth (oxytocin release) or blood clotting, it is less common for target organs to regulate pituitary function through this method, as it can lead to instability.
Choice B rationale
Negative feedback is the predominant mechanism by which target organs regulate pituitary function. High levels of target gland hormones inhibit the release of stimulating hormones from the pituitary and hypothalamus, thus maintaining hormonal homeostasis and preventing overproduction or underproduction.
Choice C rationale
Neural stimulation involves direct nerve impulses influencing hormone release, as seen in the adrenal medulla's response to sympathetic nervous system activation. While the hypothalamus has neural connections to the pituitary, direct neural stimulation from target organs is not the primary regulatory mechanism for pituitary control.
Choice D rationale
Direct hormonal release from target organs without involving feedback loops would result in unregulated hormone secretion, disrupting endocrine balance. Target organs typically release hormones that, in turn, exert feedback effects on the pituitary or hypothalamus, ensuring precise control and preventing dysregulation.
Correct Answer is C
Explanation
Choice A rationale
The inferior vena cava is a large vein that carries deoxygenated blood from the lower body to the right atrium of the heart. It is typically positioned posterior to the aorta and enters the heart inferiorly, collecting blood from the lower extremities and abdominal organs, and its walls are thinner and less muscular compared to arterial structures.
Choice B rationale
The superior vena cava is a large vein that transports deoxygenated blood from the upper body, including the head, neck, and upper limbs, to the right atrium of the heart. It is situated anterior and to the right of the aorta in the mediastinum, and its venous structure distinguishes it from the thick-walled arterial vessels.
Choice C rationale
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches into smaller arteries. Its thick, elastic walls are crucial for withstanding high pressure from systemic circulation and maintaining blood flow to all body tissues.
Choice D rationale
The pulmonary artery is a large artery that carries deoxygenated blood from the right ventricle of the heart to the lungs. Unlike other arteries, it carries deoxygenated blood, a key distinction. It branches extensively within the lungs to facilitate gas exchange, and its pressure is considerably lower than the systemic arterial pressure.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.